This invention in general relates to windings for electrical rotating machines, and in particular relates to the construction of armature windings for electrical machines of the turbine generator type.
Conventional electrical rotating machines such as turbine generators commonly employ armature windings in which the individual phase coils are diamond shaped. With such windings the end connections for the coils are of a complex shape, which is generally a conical involute. The involute shape of the coil ends as a result limits the extent to which the stator shield can provide support for the winding. Heretofore it has been difficult to provide simple and strong mechanical support for the coils against radial and tangential electromagnetic forces. A generator having windings which can be supported more securely than that of an involute type winding would make it possible to accept higher force levels and thus permit the generator to be designed for increased critical fault clearing time.
In existing electrical machines such as turbine generators the complex winding shapes result in a severe limitation on the use of insulation suitable for high voltage applications. The windings of electrical generators are typically insulated by a mica type material with the result that operating voltages are limited to the order of 30 kV. It would be desirable to provide a winding configuration which would accommodate the placement of insulation of the type for use in very high voltage applications, such as up to 500 kV. A generator capable of operating at this voltage level would thereby permit direct connection to a transmission system and eliminate the need of a step-up transformer.